添加EHN对宽馏分燃料燃烧和排放特性的影响

摘要

宽馏分燃料在中、高负荷能够明显降低柴油机碳烟(soot)排放,保持较高的热效率,但在低负荷存在燃烧稳定性差的问题.硝酸异辛酯(EHN)能够有效提高燃料的着火性.笔者提出向宽馏分燃料中添加EHN的方式来改善其着火性,并对比了3种添加比例下燃料的燃烧和排放特性.结果表明:向含有50％(体积分数)汽油的宽馏分燃料(GD 50)中添加EHN能够提高燃料的十六烷值,缩短滞燃期,低负荷工况的循环变动率显著降低,燃烧稳定性得到改善.添加EHN后,GD 50燃料的总碳氢(THC)和CO排放显著降低,NOx有所升高,在供油量为11.4 mg/cyc和12.9 mg/cyc两个中等负荷工况下对碳烟排放的影响不大.添加EHN能够显著提高GD 50燃料的指示热效率.%Wide distillation fuel (WDF) can significantly reduce soot emission at medium and high loads,but has poor combustion stability at low load.It is known that ethylhexyl nitrate (EHN) can improve fuel ignitability effectively.In this work,EHN was added into WDF,and engine combustion and emission characteristics were investigated at three addition ratios of EHN.The results show that adding EHN into WDF with 50％ gasoline (GD 50) increases fuel cetane number and shortens the ignition delay.The cycle-to-cycle variation is reduced and combustion stability is improved.By adding EHN,the total hydrocarbon (THC) and carbon monoxide (CO) emissions of GD 50 are significantly reduced,and the NOx emission is slightly increased.But the soot emission remains similar at the medium conditions with fuel mass of 11.4 mg/cyc and 12.9 mg/cyc.ENH addition can significantly increase the indicated thermal efficiency of GD 50.